The Collaborative International Dictionary of English v.0.48:

Quintal \Quin"tal\, n. [F., fr. Sp. quintal, fr. Ar. qintar a
   weight of 100 lbs., prob. fr. L. centenarius consisting of a
   hundred, fr. centeni a hundred each, fr. centum a hundred.
   See Hundred, and cf. Kentle.]
   1. A hundredweight, either 112 or 100 pounds, according to
      the scale used. Cf. Cental. [Sometimes written and
      pronounced kentle.]
      [1913 Webster]

   2. A metric measure of weight, being 100,000 grams, or 100
      kilograms, equal to 220.46 pounds avoirdupois.
      [1913 Webster]

WordNet (r) 3.0 (2006):

quintal
    n 1: a unit of weight equal to 100 kilograms
    2: a United States unit of weight equivalent to 100 pounds [syn:
       hundredweight, cwt, short hundredweight, centner,
       cental, quintal]